Means for feeding apertured blanks to a thread forming apparatus



Feb. 8, 1966 J. A. MACLEAN m, EI'AL 3,

MEANS FOR FEEDING APERTURED BLANKS TO A THREAD FORMING APPARATUS Filed April 1, 1964 7 Sheets-Sheet 1 INVENTORS JOHN A.MAC LEANJII DECEASED JOY 0. MAC LEAN ADMINISTIQATOR Ll By WAN A. COUILLAIS Feb. 8, 1966 J. A. MACLEAN Ill. EI'AL MEANS FOR FEEDING APERTURED BLANKS IO 7 Shoots-Sheet a A THREAD FORMING APPARATUS Filed April 1, 1964 1966 J. A. MACLEAN m, El'AL 3,

MEANS FOR FEEDING APERTURED BLANKS TO A THREAD FORMING APPARATUS Filed April 1, 1964 7 Sheets-Sheet 5 z 196 m 198 18% 197 M6 ass M0 M8 M5 INVENTORS JOHN A. MAC LEAN III DECEASED JOY D. MAC LEAN,ADMIN|5TI2ATOI2 BY YVAN A. COUILLAIS M, 09m, (54m a 6 @Ilttys.

1966 J. A. MACLEAN m. ETAL 3,233,259

MEANS FOR FEEDING APERTURED BLANKS To A THREAD FORMING AFPARATUS Filed April 1, 1964 7 Sheets-Sheet 6 INVENTORS JOHN A. MAC LEAN III DECEASED JOY D. MAC LEAN. ADMINISTRATOR BY YVAN A. COUILLAIS W, 94/1/60, (31% (644 mm dlttys.

Feb. 8, 1966 .1. A. MACLEAN Ill, ETAL 3,23

MEANS FOR FEEDING APERTURED BLANKS To A THREAD FORMING APPARATUS Filed April 1, 1964 7 Sheets-Sheet '7 INVENTORS JOHN A. MAC LEAN III DECEASED JOY D. MAC LEAN,ADM|NI5TRATOR BY YVAN A.COUILLA|5 United States Patent 3,233,259 MEANS FQR FEEDING APERTURED BLANKS TO A THREAD FORMING APPARATUS John A. MacLean III, deceased, late of Northhrook, 111., by Joy D. MacLean, administrator, Northbrook, and Yvan A. Couillais, Chicago, 111., assignors to MacLean- Fogg Lock Nut Co., Chicago, 111., a corporation of Delaware Filed Apr. 1, 1964, Ser. No. 356,678 20 Claims. (C1. 19-139) This invention relates to thread forming machines, and more particularly to such machines adapted to substantially continuous operation for tapping, rolling or otherwise forming threads in workpieces, such as nut blanks and the like.

One of the general objects of this invention is to provide a thread forming machine adapted to receive, thread and eject a series of parts in sequence and with the parts passing therethrough as a continuing flow.

More specifically, the invention comprehends a thread forming machine wherein blank parts are fed onto the tap at a speed of linear movement substantially synchronized with that effected by the action of the tap, thereby to accomplish what is generally known as lead screw tapping.

This invention has within its purview the provision of a thread forming machine which effects the production of substantially uniform threads from end to end of a Workpiece and avoids spreading or distortion of the threads at the end of the workpiece at which the threading operation is started by the tap or other thread forming tool, whereby all of the threads are effective to afford holding force in the use of the threaded workpiece.

Another object of the invention is to provide a thread forming machine wherein workpieces are fed sequentially to a rotating tap, or thread forming tool by feed roller means driven for rotation relative to a workpiece and embodying at least one spirally disposed surface thereon for forcing the workpiece to move linearly in parallel relationship to the axis of the feed roller means while being prevented from rotating with the tap or forming tool.

As another object, this invention comprehends the provision of a thread forming machine having a plurality of power driven rotary feed rollers for feeding a series of workpieces in spaced sequence to a tap or other thread forming tools, said feed rollers having spirally disposed surfaces thereon for forcing the workpieces longitudinally of the rollers to the tap or thread forming tool and wherein the structures and directions of rotation of the feed rollers are selected to counteract the tendency of the tap or thread forming tool to rotate the workpiece and to resist the tendency of the workpiece to get jammed between the rollers.

It is another object of the invention to provide a thread forming machine embodying a roller type feed mechanism for feeding workpieces onto a tap or other thread forming tool and means for supplying workpieces to the roller mechanism which means and roller mechanism coact to separate the workpieces as they are fed thereto, thereby to provide a continuing sequence of workpieces in generally uniformly spaced relationship to one another for threading by the tap or other forming tool.

The invention has for another object the provision of a thread forming machine having a workpiece feeding mechanism embodying a plurality of feed rollers including means on the surfaces thereof for effecting linear movement of workpieces to a tap or other tool for threading, and wherein said feed rollers are mounted for movement lateral to the axis thereof by means embodying interconnecting mechanism for moving the rollers toward Patented Feb. 8, 1966 and away from one another either by a jammed or defective workpiece or by action of an operator for the release of a workpiece from therebetween or for the insertion of a workpiece therebetween.

The invention further comprehends the provision of a thread forming machine embodying a workpiece feeding mechanism having roller means for effecting linear movement of workpieces to a tap or other thread forming tool, which roller means has parts movable laterally apart and toward one another relative to the axis of linear movement of the workpieces, and which movement of the parts laterally from one another or axially of the roller axes effects stoppage of the machine and prevents it from being started.

As another object, this invention has within its purview the provision of a thread forming machine embodying a feed mechanism having a spiral surface for moving workpieces linearly to a tap or thread forming tool and additional means for supplying workpieces in spaced relationship to the feed mechanism, said last mentioned means including a workpiece guide part having a curve adjacent one end of the spiral surface for effecting a spread of the end surfaces of the workpieces on the convex side of the curve of the guide which affords space for the spiral surface to become engaged with successive workpieces in separated relationship to one another.

The invention further has within its purview the provision of a thread forming machine adapted to use with workpieces having holes therein and which embodies workpiece feed parts wherein the workpieces are fed to the thread forming mechanism on a wire which passes through the holes in the workpieces and which is accom-. panied by other means whereby defective workpieces, such as those having no hole, a clogged hole, an off-center or undersize hole, or oversize workpieces cannot reach the thread forming mechanism, thereby to cause trouble in the operation of the machine.

This invention also comprehends a thread forming machine embodying workpiece feeding means substantially synchronized with normal movements of the workpiece along a tap or thread forming tool, and which feeding means has parts movable during use to maintain the work piece in properly oriented relationship to the tap or thread forming tool, even though burrs or other imperfections may be present on the exterior surfaces of the workpiece. As another object, this invention further has within its scope the provision of a thread forming machine embodying a tap or thread forming tool to which workpieces are fed at one end and which includes a crank-type stem at the opposite end over which threaded workpieces pass for discharge from the machine, and through which the tap or thread forming tool is rotationally driven in use.

It is another object of the invention to provide a thread forming machine which has easily and readily operable.

means for effecting release and removal of taps or other thread forming tools for interchange purposes and wherein such release cannot be effected by forces applied to the tap or forming tool during use of the machine.

Another object of this invention is to provide a threadtapping or forming machine for use with apertured workpieces and capable of operating at a speed enabling it to form threads in the workpieces produced by a modern workpiece forming machine.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a front elevational view of a thread tapping machine embodying a preferred form of this invention;

FIG. 2 is a diagrammatic side sectional view of the machine illustrated in FIG. 1 and depicts a general relationship of operating parts of the machine;

FIG. 3 is a fragmentary view showing a portion of the structure illustrated in FIG. 1 and drawn to a larger scale, with some parts broken away to show details of the structure;

FIG. 4 is a fragmentary side sectional view taken substantially as indicated by a line 4-4 and accompanying arrows in FIG. 3;

FIG. 5 is a fragmentary top sectional view taken substantially at the position indicated by a line 5-5 and accompanying arrows in FIG. 3;

FIG. 6 is an end elevational view of a portion of the structure depicted in FIG. 5, drawn to a larger scale, and viewed as indicated by a line 66 and accompanying arrows in FIG. 5;

FIG. 7 is a fragmentary sectional view taken substantially as indicated -by a line 77 and accompanying arrows in FIG. 6;

FIG. 8 is an end sectional view of a portion of the structure shown in FIG. 5 and wherein the section is taken substantially as indicated by a line 8-8 and accompanying arrows in FIG. 5, FIG. 8 being drawn to a larger scale than FIG. 5;

FIG. 9 is a broken fragmentary sectional view taken substantially as indicated by a line 99 and accompanying arrows in FIG. 8;

FIGS. 10, 11 and 12 are respectively side elevational, bottom and end views of a part of the structure illustrated in FIG. 9;

FIG. 13 is a fragmentary front elevational view of parts of the structure depicted in FIG. 3, with those parts moved to positions different from those shown in FIG. 3;

FIG. 14 is a fragmentary sectional view taken substantially as indicated by a line 1414 and accompanying arrows in FIG. 13;

FIGS. 15 and 17 are diagrammatic views indicating parts of the structure shown in FIG. 3;

FIG. 16 is a fragmentary side sectional view taken substantially as indicated by lines 1616 and accompany arrows in FIG. 15 and depicts a preferred form of parts of the machine utilized for feeding plain hexagonal work pieces in the machine;

FIGS. 18, 19 and 20 are views similar to FIG. 16 and taken at positions such as those illustrated by lines 1818 and accompanying arrows in FIG. 17, and wherein each illustrates a modified form of the machine parts utilized for feeding flanged workpieces in the machine;

FIG. 21 is a diagrammatic view illustrating some of the essential parts of the drive mechanism for parts of the machine; and

FIG. 22 is a plan view depicting one manner of producing parts utilized in the illustrated machine.

Reference is first made to FIGS. 1 and 2 to provide a general understanding of the exemplary embodiment of this invention which is disclosed herein for illustrative purposes. These views depict the general layout, organization, part relationships and operative organizations of a complete thread tapping machine 25 which is adapted substantially for continuous operation for threading workpieces, such as nut blanks. In the disclosed structure, it is understood that the workpieces which are to be threaded have a bore or pierced aperture therein, in the surface of which the threads are to be cut by a tap 26. The work-pieces or blanks, in this instance, are supplied to the functional parts of the machine through means such as a hopper 27, although it is understood that other such means may be provided, or that the workpieces may be fed directly to this machine from a blank forming machine without material change of the functioning, relationships or operating principles of the principal functional parts.

In the form disclosed, the apertured workpieces are fed through a tubular housing 28 and onto a rod or wire 29 which extends through the apertures thereof and along 'which the workpieces gravitate to a feeding mechanism which includes a plurality of feeding rollers 33, 32 and 33. As will be more fully explained and described, the feeding rollers effect removal of the workpieces in spaced relationship to one another and feed them onto the tap 26 in such spaced relationship; the feeding rollers and the tap both being driven from a suitable prime mover, such as an electric motor 34 having a drive shaft 35, at speeds which are substantially synchronized with respect to the rate of movement of the workpieces along the tap and as induced by the feeding rollers.

The tap 26 has a relatively long stem 36 thereon which includes a curved crank portion 37 and which extends through a rotationally driven housing 38 from which the tap is driven. The stem extends from the end of the tap opposite that onto which the workpieces are fed by the feeding rollers from the rod or wire 29, whereupon such workpieces which have been threaded by the tap move along the stem, through the housing 38 and are discharged from an end portion 39 of the stem along the center line of the tap and without radial velocity. The rotatable housing 38 is mounted for rotation in a portion 40 of the machine housing 41 which is supported from a base or floor structure through legs 42; the driving connection, in this instance, being provided by a drive chain 43 (FIG. 5) which drivingly engages a sprocket 44 on the motor shaft 35 and a sprocket 45 on one end of the rotatable housing 38. The driving rollers 30, 32 and 33 are driven from the motor shaft 35 through a gear chain 46 which is illustrated generally in FIG. 2 and in greater detail in FIG. 21.

As the workpieces are threaded, a continuous stream of liquid coolant is projected onto the workpieces and the tap from a nozzle 47 which is supported from the machine housing at a position above and to one side of the tap axis, as shown in FIG. 1. Coolant liquid is fed to the nozzle 47 through a conduit 48 from a sump tank 49 with the aid of a pump 50. Coolant is collected below the tap 26 and feed rollers by a collector trough 52 and returns to the sump tank 49 through the trough. A screen 53 is supported near the top of the trough 52 to strain metal chips from the coolant as the coolant circulates, and which chips are cut from the workpieces by the tap 26. The chips may be periodically removed from the screen 53 and collected in a pan 54 at the front of the machine. The sump tank 49 is supported between the lower portions of the legs 42 of the machine below the trough 52. As shown in FIGS. 1 and 3, splash guards 55, 56 and 57 are supported at the front of the machine and extend along the feeding rollers 30, 32 and 33 to limit the splashing of coolant and to direct the flow thereof into the trough 52.

Having more detailed reference to the structure, and more particularly the portions thereof illustrated in FIGS. 4, 5, 6, 7, 8, 9 and 10 to 12 inclusive thereof, the rotary housing 38, through which the tap 26 and its stem 36 are supported and driven, an outer cylindrical shell 58 has therein a filler block 59 having therein a generally rectangular slot 60 which extends longitudinally of the filler block and housing from end to end of the filler block and into the block from one peripheral surface thereof to a depth beyond the center of the block, as shown in FIGS. 5, 8 and 9. Fitting snugly and slidably into the slot 60 is an inner block 62 composed of two outer plates 63 and 64 hingedly connected-together for swinging movements relative to one another about a longitudinal axis of hinge pins 65 and 66 which, in the assembled relationship of parts, as shown in FIG. 8, is disposed at the bottom of the slot 60. To provide this. hinge connection in the disclosed structure, the outer plate 63 has angularly projecting bosses 67 and 68 near opposite ends thereof which project and fit movably and snugly between pairs of projecting bosses 69 and 7d and '72 and '73 near opposite ends of the outer plate 64. In this instance, the hinge pins 65 and 66 comprise cylindrical screws extending through bores in the bosses 69, 67 and 70 at one end of the filler block and through bosses 72, 66 and 73 at the other end of the filler block with end portions 74 and 75 threaded into the bosses 70 and 72 respectively. Segmental plates 76, '77 and 78 are mounted on the inner surface of the outer plate 63 and are each located relative to the outer plate 63 by locating pins 79; said segmental plates 76, 77 and 78 being grooved, as by milling, to define half of a hexagonal opening 80 extending longitudinally through the inner block and longitudinally contoured to conform to the general longitudinal contour of the crank portion 37 of the stem of the tap. Similar segmental plates, such as 82 in FIG. 8, are mounted in like manner on the outer plate 64 and are grooved in a like and opposed manner to provide the other half of the hexagonal opening 80 when the inner block is in its closed and assembled relationship with respect to the filler block 59.

The inner block 62, with the segmental plates mounted between the outer plates 63 and 64 is slidable into the slot 60 from the outer end of the rotatable housing to its operative position therein. It may be understood that when the inner block is in place within the rotatable housing, the stem of the tap is confined within the opening 80, while when the inner block is removed from the rotatable housing, the tap and its stem are removed from the machine therewith, and the tap stem may be removed from the opening 80 by separating the outer plates 63 and 64 and the respective segmental plates which are mounted thereon. At the outer end of the inner block 62, a relatively thick circular plate 83 is secured to the outer plate 63 by fastening means, such as a screw 84 (FIG. 5) and the outer hinge pin 65. The plate 83 fits snugly into the outer end portion of the inner surface of the shell 58. A hollow cylindrical handle 85 has a flange 86 thereon which mounts against the circular plate 83 and fits into the inner end of the bore in a ring 91, while the handle projects axially from the end of the shell and has a bushing 87 therein which has an opening 88 therethrough and is pressed into the plate 83, the inner end of which bushing is aligned with the outer end of the hexagonal opening 80 in the segmental plates. An outer end plate 89 has an opening 90 which fits over the handle 85 and is mounted against the flange 86 on the handle. As shown in FIG. 5, shouldered screws 92 and 93 are threaded into bores 94 and 95 respectively in the outer end plate 89 and extend into the inner block and filler block assemblies. These screws and their heads are movable longitudinally through openings 96 and 97 in the circular plate 83 and have compression springs 98 and 99 mounted thereon between the screw heads and the ring 91 to bias the outer plate 89 against the outer surface of the flange 86. Also, the screws 92 and 93 are slidable in openings 100 and 102 in a ring 91 which encompasses the flange 86 on the handle and is secured to the circular plate 83. Thus, when axial outward force is exerted on the handle 85, the flange 86 and the outer plate 89 move away from the outer end surface of the circular plate 83.

As shown in FIG. 7, movable retaining latch slides 103 and 104 are slidably mounted in radial openings 105 and 106 in the circular plate 83 for radial movement into and from engagement with an inner retaining groove 107 which extends peripherally of the inner surface of the shell 58. These retaining latch slides 103 and 104 are displaced in 90 relationship to the shouldered screws 92 and 93 which carry the biasing springs 98 and 99, as iridicated in FIG. 6. Latch actuators 108 and 109 are mounted for axial sliding movement in openings 110 and 112 in the circular plate 83 and move through slots 113 and 114 respectively in the latch slides 103 and 104. Pins 115 and 116 are secured to the mid-regions of the latch slides 103 and 104 and extend across the slots 113 and 114 respectively in the latch slides and also extend through diagonally disposed slots 117 and 118 in the latch actuators 108 and 109. The latch actuators are secured to the outer end plate 89 by projecting end portions 119 and 120. Thus, when the handle 85 is gripped and force is exerted axially thereof in an outward direction, the latch actuators 108 and 109 move axially with the handle 85, the flange 86 thereon and the outer end plate 89, whereupon the pins 115 and 116 move inwardly in the slots 117 and 118 to effect inward movement of the latch slides 103 and 104 to release the ends of those latch slides from the groove 107 of the housing. This outward movement of the handle and other parts is effected against the biasing forces of the compression springs 98 and 99, and provides for removal of the inner block assembly and the tap axially from the shell 58 and filler block 59 of the rotatable housing 38. When thus removed, the plates 63 and 64 may be swung apart about their hinge axes and the tap and its stem may be removed therefrom for replacement. When these parts of the machine are to be reassembled, the tap and its stem are put in place, the plates 63 and 64 are brought together and the assembly is moved axially back into the slot 60 within the rotatable housing 38. When the inner block assembly and the tap are returned to their operative positions within the rotatable housing 38, the latch slides 103 and 104 re-engage the groove 107 in the shell 58 to retain the parts in place with the aid of the action of the compression springs 98 and 99.

At its inner end, the rotatable housing has a stub 122 secured thereto by fastening means, such as screws 123, as shown in FIGS. 5 and 9. Between the hub 122 and the end of the shell 58 is a spacer ring 124 held in place by the same screws 123 which secured the hub to the rotatable housing. Internally of the shell 58 and the hub 122 are shoulders 125, 126 and 127 which conform generally to the inner block 62 of the rotary housing. An anti-friotion bearing 128 is mounted on the hub 122 and located axially of the hub by a shoulder 129 thereon, which bearing is supported by a wall 130 of the machine housing 41, as shown in FIGS. 4 and 5. On the bulb 122, the bearing 128 is held in place against the shoulder 129 by a snap ring 132 which is mounted in a groove in the hub and has a peripheral portion extending outwardly to engage the end of the bearing in opposed relationship to the shoulder 129. Also, an outer snap ring 133 is engaged in a groove in the outer race of the bearing 128 and has a peripheral portion engaged in -a groove 134 in the wall 130 and held in place by support and spacer plates 135 and 136. This supports the inner end of the rotatable housing 38 for rotation.

The outer end of the rotatable housing 38 is supported for rotation relative to the machine housing 41 by three bearings 137, 138 and 139 which are spaced in substantially 120 relationship to one another with respect to the periphery of the rotary housing, as indicated in FIG. 6. Each of the bearings 137, 138 and 139 is mounted on a support shaft 140 having an eccentric portion 142, as indicated in FIG. 5, for the bearing 137. Opposite end portions 143 and 144 of the shaft 140 on opposite sides of the eccentric portion 142- are in concentric and coaxial relationship to one another and are supported for rotation by end rings 145 and 146 of the machine housing 41 which are secured together by an outer ring 147, which outer ring also forms an outer enclosure for the bearings. In the assembly, the bearing is held in place against a shoulder 148 on the shaft 140 by a spacer ring 149 which also engages the end ring 146 of the machine housing. Externally of the machine housing, the shaft 140 has a laterally projecting tab 150 thereon, which tab is arcuately slotted and held in position by means such as a screw 152, so that the shaft may be swung rotationally between limits to vary the position of its eccentricallly supported bearing radially of the outer surface of the periphery of the shell 58 of the rotary housing 38. Thus, by adjustment of the positions of the shafts 140, the bearings can be brought into contact with the peripheral surface of the shell 58 and the bearings may be brought into concentric relationship with respect to the axis of the bearing 128 at the other end of the rotary housing. In the disclosed structure, a dirt seal 153 is mounted in a peripheral groove 154 in the end ring 145 and is held in place by a ring 155 which is secured to the plate 145 by screws, such as 156.

Internally of the bushing 122 at the inner end of the rotary housing 38, as shown in FIGS. and 9, is a bushing 157 having a flange 158 at one end engaging a radial shoulder 159 on the interior of the bushing, and having a cone nut 160 threaded onto the other end thereof which engages the end of the hub 122 to hold the bushing in place within the hub. The bushing 157 has an axial cylindrical bore 162 therein through which workpieces pass on the stem 36 of the tap after the tap 26 passes through the workpiece-s. At the end of the bus ing 157 adjacent the opening 80 in the segmental plates and aligned therewith is a guide ring 163 located between an internal shoulder 164 of the bushing and the segmental plate 78. This guide ring has a hexagonal opening therethrough which is in register with the hexagonal opening through the segmental plates. Thus, as the workpieces pass along the tap stem 36 through the circular portion of the bore 162 of the bushing 157, they do not necessarily rotate at the same speed as the stem of the tap which is driven through the rotary housing 3 8.

As a result, additional mechanism is required to bring the workpieces into registry with the opening in the guide ring 163 for passage to and through the opening in the segmental plates; it being understood that the hexagonal contour disclosed herein is only exemplary, and that other peripheral contours, such as square, octagonal or circular, for example, might be used with the same general principles of structure involved. For effecting initial rotation of the work-pieces with the rotary housing 38 and for effecting their proper alignment with the opening in the guide ring 163, keys 165 are mounted in radial slots 166 in the wall of the bushing 157 in equally and peripherally spaced relationship to one another. For the presently disclosed hexagonal workpiece contours, the keys are spaced in 120 relationship with respect to one another in the wall of the bushing 157. As shown in FIGS. 10, 11 and 12, the keys 165 have shoulders 167 thereon which prevent them from passing through the openings 166 and into the bore of the bushing 157. The keys 165 are held in place by resilient snap rings 168 which encompass the keys and are in axial spaced relationship to one another. The keys are contoured to have an edge 169 which extends longitudinally thereof and which is tapered to merge with the circular inner surface of the bore 162 of the bushing 157 at the end of the keys from which the workpieces approach the keys through the bore. These edges engage the flat surfaces of the workpieces and turn the workpieces into registry with the surfaces of the opening in the guide ring 163 as the workpieces move along the stem 36 of the tap toward that guide ring. At the same time, the workpieces are rotated by the engagement with the keys to bring them into synchronism with the rotation of the rotary housing.

The sprocket 45, through which the rotary housing 38 is driven by the chain 43 from the sprocket 44 on the motor shaft 35 is on the peripheral surface of the hub 122 adjacent the end of the shell 58. It may be readily understood that the relationship of the sizes of the sprockets 44 and 45 and the speed of rotation of the motor 34 control the speed at which the tap 26 is driven. As depicted in FIG. 5, the housing includes plates 170 and 172 on opposite sides of the sprockets 44 and 45 and the chain 43, which plates are spaced therefrom and between which the drive chain passes. At one side of the housing, a cap 173 is provided and has a flange portion 174 thereon which fits into an opening 175 in the outer housing 41 to provide access to the driving chain. The driving motor 34 is mounted on the plate of the outer housing and is secured in place by fastening means, such as screws 176, with a spacer ring 177 located between the plate 170 and the end surface of :the motor. The motor shaft 35 passes through an opening 178 in the plate 170. When the machine is to be started, proper orientation of the tap stem 36 within the opening 80 is provided by placing a series of workpieces on the stern within the opening which workpieces are pushed from the stem as successive workpieces pass across the tap 26 and onto the stern.

With the tap thus supported and driven, the next consideration is the structure provided for feeding the workpiece blanks to the tap for internal threading, and in this respect the provision of a feeding mechanism which is adapted to the threading of workpieces in continuous and spaced relationship to one another and the feeding of the workpieces to the tap at a speed substantially synchronized with the speed of movement of the workpieces along the axis of the tap, when the tap is being driven at its normal and predetermined speed. Having reference to FIGS. 3, 4 and 5, as well as FIGS. 13 and 14, the feeding rollers 30, 32 and 33 have similar spiral ribs 179, 180 and 182 projecting radially from the peripheral surfaces thereof, which spiral ribs are spaced axially along the respective roller-s at equal distances for receiving workpieces therebetween and in predetermined spaced relationship to one another. As shown in FIGS. 15 and 16, three feeding rollers are utilized for hexagonal workpieces 183, and in their operative relationship to the workpieces, the feeding rollers have cylindrical surfaces 184, 185 and 186 between the spiral ribs, which cylindrical surfaces engage alternate flat surfaces 187, 188 and 189 of the workpieces by virtue of the 120 disposition of the axes of the feeding rollers with respect to the centers of the workpiece apertures 190 and the axis of the tap 26. For effecting movement of the workpieces axially of the feeding rollers and toward the tap 26, an end surface of each workpiece is engaged by side surfaces of the projecting ribs of the feeding rollers, as indicated in FIG. 16.

As shown in FIGS. 13 and 14, the feeding rollers 30, 32 and 33 respectively are mounted on crank-type supporting pieces 192, 193 and 194; the mounting and driving structures for each driving roller being substantially alike, although the crank-type supporting pieces 192, 193 and 194 are somewhat different in their individual structures. That is, as shown in FIG. 14, the driving roller 33 has a counterbore 195 extending axially of the interior thereof and a bore 196 which extends from the inner end of the counterbore to the adjacent end of the feeding roller. The crank-type supporting piece 194 has a projecting hollow hub 197 thereon which carries bearings 198 and 200 at its opposite end regions. Also, a bearing 199 is carried by the roller 33 in coaxial relationship to the bearings 198 and 200. The bearings 198 and 200 support a spindle shaft 202 for rotation within the hub 197. The spindle shaft has'a driving gear 203 mounted at one end thereof, and at the end of the spindle shaft opposite the gear 203, ithas a portion 204 which projects beyond the hub 197 and serves as a support and driving connection to the outer end of the feeding roller. A key 2415 provides a driving connection between the end portion 264 of the spindle shaft and the feeding roller, and a second projecting portion 2116 of the spindle shaft is threaded to receive an end 207. A Washer 263 is disposed between the end and a shoulder 209 at the end of the portion 204 of the spindle shaft and projects outwardly in a radial direction to overlap an end surface 210 of the feeding roller to hold the feeding roller in place axially of the spindle shaft. Also, a spacing washer 212 is provided between an end surface 213 of the counterbore 195 and a shoulder 211 on the spindle shaft 202. Near the 9 end of the feeding roller opposite the keyed connection to the spindle shaft 202, the feeding roller is rotatably supported relative to the external surface of the hub 197 by the bearing 199. A dirt and oil seal 215 is provided between the hub 197 and the inner end of the feeding roller and is held in place by washers 216 and 217 on opposite sides thereof. With this structure, it may be readily understood that when the driving gear 203 is driven, the driving force is transmitted through the spindle shaft 202 to the feeding roller which rotates relative to the hub 197.

The supporting pieces 192, 193 and 194 are similarly mounted for both axial and swinging movements relative to supporting parts on the machine frame. In each instance, the supporting structures are similar and are like that shown in FIG. 14 for the feeding roller 33. That is, in addition to the feeding roller supporting hub 197, the crank-type support has thereon an oppositely projecting hub 218 which is displaced axially from the axis of the hub 197, but wherein the axes of the hubs 197 and 218 are parallel to one another. The hub 218 of the cranktype supporting piece 194 is mounted for swinging and axial movements with respect to the axis of the hub 218 on the spacer plates 135 and 136, which spacer plates are fastened to the machine housing 41. At the end adjacent the plate 136, the hub 218 has a flange 223 thereon which projects inwardly of the 'hub in a radial direction to retain a crank spring rest 224 which has a flange portion 225 engaging the inner radial surface of the flange 223 on the hub 218 and an end portion 226 which engages the spacer plate 136. A compression spring 227 is disposed between the flange 225 of the crank spring rest 224 and the head of the screw 220 to bias the crank-type supporting piece 194 toward the spacer plate 136, while providing for axial movement of the cnank type supporting piece away from the spacer plate 136 against the biasing force of the spring 227 under an abnormal force exerted against one or more of the ribs 182 of the feeding roller, as might be caused by an oversized or defective workpiece. Also, the crank-type supporting piece 194 may swing about the axis of the screw 220 as a result of an abnormal force exerted against the feeding roller 33 which might be caused, for example, by a laterally oversized or distorted workpiece, or by virtue of a workpiece becoming abnormally engaged between adjacent feeding rollers.

Mounted on the exterior of the hub 218 of the cranktype supporting piece 194 is a sleeve 228 which is pressed into plate 135 and serves as a guide and support for hub 218 and, at the same time, as a shaft for an idler gear 229 mounted relative to the sleeve on a bushing 230, and which gear 229 meshes with the gear 203 on the spindle shaft 202. Axially, the gear 229 and bushing 230 are located on the sleeve 228 by the plate 135 which constitutes a part of a crank and gear train bracket, as well as by thrust washers 233 and 234.

Since the feeding rollers 30 and 32 are supported relative to crank-type supporting pieces 192 and 193 respectively in a manner like that described with respect to the mounting of the feeding roller 33 on the crank-type supporting piece 194, it may be understood from reference to FIG. 13 that the feeding roller 30 is similarly mounted on its spindle shaft 202a and held in place by a nut 207a and a washer 208a, while the feeding roller 32 is likewise supported from a spindle shaft 202]) and held in place with respect thereto by a nut 207b and a washer 208k. Likewise, the crank-type supporting pieces for the feeding rollers 30 and 32 are supported for swinging and axial linear movements on screws 220a and 220]) respectively. When in their operative positions for receiving and feeding workpieces to the tap 26, the respective crank-type supporting pieces and their feeding rollers are in the positions illustrated in FIGS. 3, 4 and 15, while for purposes, such as the removal of defective workpieces or for providing access to the tap for any of various reasons, the crank-type 10 supporting arms may be swung outwardly to the position illustrated in FIG. 13.

It has been found convenient for operational and functional reasons that the crank-type supporting pieces 192, 193 and 194 shall be movable together about their respective axes of swinging movements provided by the screws 220a, 22017 and 220 respectively. For effecting this operation, and as shown in FIGS. 3 and 13, the crank-type supporting pieces 193 and 194 have teeth 235 and 236 thereon, which teeth are in meshing engagement and in concentric relationship to the axes of the screws 22015 and 220 respectively, whereupon when the crank-type supporting piece 193 is swung to either its outer or inner position, the crank-type support piece 194 is moved therewith.

Also, as shown in FIGS. 3 and 13, the crank-type supporting piece 193 has an outwardly projecting arm 237 thereon which is connected through a link 238 to an outwardly projecting arm 239 on the crank-type supporting piece 192; the connections of the opposite ends of the link 238 to the respective arms 237 and 239 being provided by cross pins 240 and 242. Although the movements of the crank-type supporting arms may be effected manually, if desired, the disclosed machine has a projecting arm 243 on the crank-type supporting piece 192 which is angularly disposed with respect to the projecting arm 239 and is movably connected to a piston shaft 244 of an air cylinder 245 by means such as a cross pin 246. As shown in FIG. 1, a valve 241 having a manually operative control handle 247 or a suitable solenoid valve (not shown) controls the action of the ram 245 to effect the movement thereof in either direction by controlling fluid flow to and from opposite ends thereof through conduits 248 and 249. At its rear end, the ram 245 is movably anchored and supported by a bracket 250.

As shown in FIG. 5, safety controls are provided for stopping the operation of the machine by shutting off the power to the motor 35 when the feeding rollers are moved either axially or by swinging movement away from their respective normal operative positions more than a predetermined amount. This safety control is provided by control elements, such as micro-switches 252 and 253, located in predetermined spaced relationship to angularly disposed surfaces of the crank-type supporting piece 194. The switch 252 has a movable element 254 which is engaged upon swinging movement of the crank-type supporting piece, while the micro-switch 253 has a movable element 255 which is engaged upon linear axial movement of the crank-type supporting piece away from the machine frame 41. These micro-switches are each suitably connected in the electrical circuit to the motor 34 to effect opening of the circuit in response to either the swinging or outward axial movements of the crank-type supporting piece 194.

In order to effect substantial conformity between the rates of movement of the workpieces axially along the tap 26 during the thread tapping operation and the movements of the workpieces effected by the feeding rollers 30, 32 and 33, and also to prevent either the jamming of workpieces onto the tap or a drag against the movements of the workpieces on the tap as such workpieces are being threaded, which jamming or dragging would have a tendency to produce non-uniform threads and reduce their effectiveness in use, the feeding rollers 30, 32 and 33 are driven at rates which eifect linear movements of workpieces which substantially conform to the normal linear motion produced by the tap while driven at its normal operating speed, otherwise known as lead screw-tapping. As previously indicated, the tap 26 is driven from the motor 34 through sprockets 44 and 45 and a driving chain 43. For driving the feeding rollers 30, 32 and 33, a series or chain of gears is provided, as illustrated in FIG. 21.

As shown in FIGS. 13, 14 and 21, the feed-ing roller 33 is driven by the spindle shaft 202 through a gear 203 which is drivingly connected thereto and through an idler gear 229 which meshes with the gear 233. Likewise, the feeding roller 30 is drivingly connected to the spindle shaft 292a through a gear 233a which meshes with an idler gear 22%. Also, the feeding roller 32 is drivingly connected to a gear 233]) which meshes with an idler gear 22%. Furthermore, the idler gears 229 and 22912 mesh with one another, so that those gears and their respective feeding rollers 2G3 and 23%, in the disclosed machine, are driven in opposite directions, so as to tend to prevent the friction between the workpiece surfaces and those feeding rollers from urging the workpiece into a jammed position between the feeding rollers 32 and 33 which tend to support the workpiece as it moves along its path of travel toward, along and from the tap. As shown in FIGS. and 21, the meshing idler gears 223 and 22% are driven through another idler gear 256 which meshes with the gear 22%, as well as with a gear 257. Another idler gear 258, which is similar to the idler gear 256, also meshes with the gear 257 and with the idler gear 229a for driving the feeding roller 30.

The gear 257 is coaxial with and drivingly connected to a larger gear 259 by a key 263 (FIG. 5). In the structure illustrated, the common axis of the gears 257 and 259 is provided by means such as a shouldered screw 262, which screw interconnects a plate 263 with a projecting portion 264 of the crank and gear train bracket piece 135. As shown in FIG..5, plates 265 and 266 are secured to and form a part of the plate 263 and are movably mounted on opposite sides of the portion 264 of the piece 135'. The shouldered screw 262 is threaded into the plate 266 and a block 267 and provides a hinge connection for swinging movement of the plate 263 relative to the piece 135 and about the axis of the gears 257 and 259.

A gear 268 meshes with the gear 253, and provides a driv- 5 ing connection between that gear 259 and a gear 269. As shown in FIG. 5, the gear 268 is supported for rotation relative to the plate 263 by means such as shouldered screw 270, and the gear 269 is supported for rotation relarelative to the plate 263 by means such as a shouldered screw 272. Also, the gear 269 and a changeable gear 273 are coaxially and drivingly connected together. The changeable gear 273 meshes with, and is driven by a gear 274 which is keyed to the shaft 35 of the motor 34. With this arrangement of gears, the speed of rotation of the feeding rollers 30, 32 and 33 may be changed with respect to the speed of the motor by changing the changeable gear 273. To effect this change and to have the changeable gears 273 of different sizes mesh with the gear 274 on the r motor shaft, the plate 263 is swung about the axis of the screw 262 when a holding screw 275 (FIG. 21) is loosened. This holding screw extends through a slot 27 6 in the plate 263 to provide a suflicient range of movement of the plate 263. Such a change of the driven speeds of the feeding rollers 30, 32 and 33, as well as a change of the tap, is utilized for changing from coarse to line threads in like sizes .of workpieces. If the sizes of the workpieces are changed within limits, compensation may be made for such changes by changing the feeding rollers 30, 32 and 33, as well as by correlating the changed feeding rollers with a proper size of the changeable gear 273. The tap, of course, in each instance corresponds to the feeding rollers and their driven speed to provide the lead screw tapping effect.

Having reference to FIGS. 2, 4 and 5, it may be observed that the top feeding roller 30 is shorter than the lower feeding rollers 32 and 33. This difference of the respective lengths of the feeding rollers serves useful purposes in connection with the feeding of workpieces to and into the feeding rollers. As has been previously mentioned, the apertured workpieces 183 are fed in a series downwardly along the feeding rod or wire 23 through a tubular housing 23. At the lower end of the housing 28 and secured thereto by a ring 277 is a hook 278 spaced from the lower end of the tubular housing 28 and which is in position to engage workpieces on the rod or wire 29 to prevent that rod or wire from falling out of the tubular housing when the feeding rollers are separated, as shown in FIG. 13.

The feeding rod or wire 29 has a bend 279 therein and a projecting end portion 28% extending along a midposition between the feeding rollers in their operative positions and in substantial alignment with the axis of the tap 26. As the apertured workpieces feed along the rod or Wire 29 at the bend 27?, their upper regions engage one another, while the lower regions thereof separate as a result of the progress along the larger radius portion of the bend. The separation between successive workpieces is sufficient to space the workpieces on opposite sides of successive convolutions of the ribs 183 on the longer and lower feeding rollers 32 and 33. These lower feeding rollers 32 and 33 move the separated workpieces inwardly in an axial direction along the feeding rollers and along the end portion 280* of the rod or wire 29 until they are engaged by the ribs on the feeding roller 30, as well as by those on the feeding rollers 32 and 33. When thus engaged by the three feeding rollers, the workpieces move off of the end portion 280 of the rod or wire 29 and are then moved onto the tap 26 in their spaced relationship to one another. After each workpiece has moved across the tap 26 and has been threaded thereby, the feeding rollers 30, 32 and 33 continue to move the workpieces along the stem 36 of the tap and into the bore 162 in the bushing 157, wherein the successive workpieces engage one another and are pushed through the rotatable housing 38 and off of the discharge end 39 of the tap stem. Inasmuch as the tap is driven, as explained, and effects linear movement of the workpieces as they are threaded, it may be understood that the relative linear feeding speeds of the tap and the feeding rollers 30, 32 and 33 must be so related that the feeding rollers do not cause the workpieces to bind on the tap or force the tap to distort the threads which are cut into the workpieces. Thus, the relative speeds of the tap and the workpieces may be such that when the tap is engaged and the workpieces are held against rotation by engagement with the cylindrical surface portions of the rollers, the tap and the rollers together are utilized simultaneously to effect the linear motion of the workpieces which provides the lead screw tapping effect.

As illustrated in the modification depicted in FIGS. 17 and 18, the same general arrangement of parts and a comparable mechanism may be utilized for feeding apertured and outwardly flanged workpieces 1813f. In this structure, the spirally disposed ribs 179, and 182 of the feeding rollers 30, 32 and 33 of the previously described structure are replaced on feeding rollers 30c, 32c and 330 by spiral grooves 282, 233 and 284, and the feeding of the workpieces in spaced relationship along the feeding rollers is effected by the engagement of flange surfaces 285 with surfaces 286 and 237 of the feeding rollers, such as 30c and 33c which are shown in FIG. 18.

In FIG. 19, another modification of the feeding roll structure for feeding flange-type workpieces is depicted. In this form, feeding rollers 33d and 33d have thereon spirally disposed ribs 179a and 182a respectively, somewhat similar to those utilized in the form illustrated in FIGS. 15 and 16, in addition to intervening spirally disposed grooves 282a and 284a which receive the flanges of the workpieces. As herein illustrated, engagement of the ribs 17% and 182a of the feeding rollers with an unfianged end surface 288 of the workpiece effects the linear movement of the workpieces along the surfaces of the feeding rollers.

As in the form illustrated in FIG. 19, the modification of FIG. 20 embodies feeding rollers such as 3% and 33e which include both spirally disposed ribs 17% and 13% and spirally disposed grooves 28212 and 28412 for accommodating the workpiece flanges and efiecting linear movement of the workpieces along the feeding rollers. In this instance, the adjoined surfaces 289 of adjacent grooves and ribs engage flanged end surface portions 290 of the workpieces to produce the linear movements of the workpieces along the feeding rollers.

FIG. 22 illustrates one manner of producing the segmental plates 76, 77 and 78 which, together, form the separable halves of the structure illustrated in FIG. 8, having the hexagonal opening 80 extending longitudinally therethrough. As shown, a substantially square plate 292 has a circular groove 293 turned therein, which groove is in the form of a half of a hexagon, in section, with vertices of the complete hexagon coinciding with flat faces of the plate, After being thus turned, the plate 292 is cut diagonally along lines 294a, 294b, 295a and 29512. In addition, the plate 292 is cut along lines 296, 297, 298, 299, 300 and 302 to bring the parts to their respective outer dimensional sizes. After being thus cut apart, the segmental plate 76 is placed with its out side edge 2941) extending along the out side edge 295a of the segmental plate 77. Also, the segmental plate 78 is placed with its out side edge 295b extending along and coinciding with the out side edge 294a of the segmental plate 77, whereupon the parts assume the positions shown in FIG. 5. It may be understood that these segmental plates may be made in different ways and that the curvatures of-the milled grooves in the segmental plates may be changed to vary the longitudinal contours of the opening 80, but the illustrated structure provides one operative combination and surface as a convenient manner of production.

From the foregoing description and by reference to the accompanying drawings, it may be understood that the machine disclosed herein is adapted to generally continuous operation for the threading of workpieces and has provisions made therein for feeding the workpieces to a tap at a rate substantially synchronized with that of the operation of the tap, while keeping the workpiece in predetermined spaced relationship to one another while being fed to and from the tap, and which machine is readily changeable in certain respects for altering the pitch of the tapped threads, changing taps and for changing work-' piece sizes or types, as well as having provisions for safety in the use thereof through automatic stoppage of the machine if a defective workpiece is encountered or for manually controlling the operations of the machine and certain operating parts thereof. In addition, the disclosed machine is relatively simple in operation and embodies parts which are readily accessible for service or change.

Having thus described our invention, what is claimed is:

1. A thread tapping machine for sequentially cutting internal threads in a series of apertured'workpieces of su'bstantiallylike size and structure and comprising, in combination, a supporting frame structure, a tap journalled for rotation about an axis and relative to the frame structure, said tap having a generally crank-shaped stem including end regions which are substantially coaxial to the tap and a curved mid-region, said end and mid-regions beingof smaller diameter than that of the tap and along which workpieces move afterpassing across the tap, means for feeding workpieces to the end of the tap opposite the stem. and including rollers supported for rotation relative to the frame structure and having axes of rotation symmetrically disposed about the axis of the tap, said rollers extending along saidtap and beyond opposite ends thereof and having, surfaces on the peripheries thereof extending spirally therealong for engagement-with portions of the workpieces to move workpieces toward the end of the tap opposite the stern thereof during rotation of the rollers, a prime mover, separate means for driving said rollers and said tap from the prime mover at speeds such that the movements of the workpieces by the rollers are substantially synchronized with the normal movements of the workpieces along the tap, and means for supplying workpieces sequentially to said means for feeding the workpieces to the end of the tap.

2. A thread tapping machine as defined in claim 1, and wherein said curved mid-region of the crank-shaped stem is surrounded by a housing supported for rotation relative to the supporting frame in substantially concentric relationship to the axis of rotation of the tap, and said housing having means therein for engagement with workpieces on the curved mid-region of the stem for transmitting driving force from the prime mover for effecting rotation of the tap.

3. A thread tapping machine as defined in claim 2, and being further characterized 'by said housing having an end cap at the end thereof opposite the tap and through which one end region of said stem extends, and means releasably holding the end cap in place relative to the housing and removable therefrom for effecting removal and installation of the tap.

4. A thread tapping machine as defined in claim 1, and further characterized by said means for supplying workpieces sequentially to said means for feeding the workpieces to the end of the tap and including workpiece guide means along which the workpieces move, said workpiece guide means having a curve therein adjacent at least one of said rollers which effects separations between end regions of adjacent workpieces, and the spirally extending surface of the adjacent roller engaging the separated end regions of workpieces to feed such workpieces to thetap in spaced relationship to one another.

5. A thread tapping machine as defined in claim 1, and wherein said workpieces have generally flat side surfaces, said rollers have surfaces for engagement with the side surfaces of the workpieces to prevent rotation of the workpieces by forces applied thereto by the action of the tap, and directions of rotation of the rollers differ in order to resist the tendency of the workpieces to become jammed between the rollers.

6. A thread tapping machine as defined in claim 1, and wherein said rollers 'are of different lengths with the longer thereof extending along a portion of one side of said means for supplying workpieces thereto for effecting intitial engagement of the workpieces with the rollers.

7. A thread tapping machine as defined in claim 1, and wherein said rollers are mounted for rotation on stud shafts which are supported at one end by plates, said plates being mounted for movements relative to the supporting frame structure in directions lateral to the axes of said stud shafts for moving the rollers apart and toward one another, and said plates being connected by mechanism such that movements of one of the plates effects substantially corresponding movements of the other.

8. A thread tapping machine for sequentiall cutting internal threads in a series of apertured workpieces of substantially like size and structure and comprising, in combination, a support structure, a tap having a longitudinal axis, means supporting the tap for rotation about its said longitudinal axis, said tap having a free end to which workpieces are fed for threading and an integral stem at the other end along which workpieces move for discharge therefrom after being threaded, means for feeding workpieces to the free end of the tap at a speed substantially equal to the normal rate of movement of workpieces along the tap while being threaded, said means for feeding workpieces to the tap including a plurality of rollers having axes substantially parallel to that of the tap and extending along the tap and beyond both ends thereof in spaced relationship thereto laterally of the tap axis, said rollers having at the peripheries thereof spirally disposed workpiece engaging surfaces for moving the workpieces to, along and beyond the tap, a prime mover, separate means for driving the rollers and the tap from the prime mover at speeds such that the movements of c the workpieces by the rollers are substantially synchronized with the normal movements of the workpieces along the tap, and means for supplying workpieces to the rollers.

9. A thread tapping machine as defined in claim 8, and wherein said means for supplying workpieces to the rollers comprises a rod extending through a series of the apertured workpieces and having a generally upright end portion along which the workpieces gravitate, said rod also having a bend therein adjacent one end of one of said rollers and a second end portion extending along said one of the rollers toward the tap.

in. A thread tapping machine as defined in claim 9, and wherein end regions of said workpieces are separated as the workpieces move along said bend in the rod, and the separated end regions of successive workpieces are engaged by said spirally disposed workpiece engaging surfaces to move the workpieces to the tap.

11. A thread tapping machine as defined in claim 9, and wherein said rollers are of different lengths, and said one of the rollers extends alongside the bend in said rod, while another of the rollers extends along the second end portion of said rod and terminates in spaced relationship to the generally upright end portion of said rod.

12. A thread tapping machine as defined in claim 8, and wherein said rollers have surfaces between said spirally disposed workpiece engaging surfaces which engage the workpieces to prevent the turning of the workpieces with and by the tap as the tap is driven.

13. In a thread tapping machine, means for feeding workpieces to a tap having a fixed axis and rotationally driven at a substantially uniform speed and comprising, in combination, a plurality of generally cylindrical rollers, means supporting said rollers for rotation about axes parallel to and spaced laterally from the axis of the tap,

said rollers having helical outer surface means by which the workpieces are moved longitudinally to, along and from the tap during rotation of the rollers, and means for driving the rollers at a speed proportional to the speed of rotation of the tap and at which movement of the workpieces by the r-ollers is synchronized with that of the normal movement of the workpieces along the tap.

14. In a thread tapping machine, means for supplying apertured workpieces in sequence and spaced relationship to a tap, said means comprising a tap having a longitudinal axis, means supporting the tap from one end so that the other end thereof is exposed, a rod along which the apertured workpieces are slidable when the rod extends through the apertures in said workpieces, said rod having a bend therein which effects separation between end regions of adjacent workpieces, and means for feeding said workpieces from said rod to the exposed end of the tap after the workpieces have passed the bend in the rod, said workpiece feeding means including means for entering the separations between successive workpieces at the bend in the rod at spaced time intervals and having surfaces for engagement with the workpieces for moving them to the tap.

15. In a thread tapping machine as defined in claim 14, the combination being further characterized by motive means for rotating the tap at a predetermined substantially uniform speed, and means separate from the means for rotating the tap for driving said workpiece feeding means at a speed proportional to that of the tap.

16. In a threaded tapping machine for apertured workpieces having predetermined contours, a tap having a stem extending from one end thereof, said stem including in the mid-region thereof a curved crank-type segment, cylindrical tap driving means encompassing and extending along said curved crank-type segment of the stem and including therein separable elements which together define an opening having a sectional shape and size conforming generally to said predetermined contours of the workpieces and providing a passage through which said workpieces are slidable, said tap driving means being spaced from the tap longitudinally of the stern, means between the tap andthe' tap driving means'for'rotationally orienting the workpieces on the stem to positions for movement into said passage, and said separable elements being made up of a plate initially made with a circular channel therein conforming to substantially half of said predetermined contours of the workpiece and then divided into segments which are transposed and adjoined to form the separable elements having general longitudinal conformity to a portion of said stem including the curved crank-type segment thereof.

17. In a thread tapping machine for apertured workpieces having predetermined contours, a tap having a stem extending from one end thereof, said stem including in the mid-region thereof a curved crank-type segment, cylindrical tap driving means encompassing and extending along said curved crank-type segment of the stem and including therein separable elements which together define an opening having a sectional shape and size conforming generally to said predetermined contours of the workpieces and providing a passage through which said workpieces are slidable, said tap driving means being spaced from the tap longitudinally of the stem, means between the tap and the tap driving means for rotationally orienting the workpieces on the stem to, positions for movement into said passage, said cylindrical tap driving means further including a hollow cylindrical outer shell, cap means for the end of the shell opposite the tap, said separable means being secured to the cap means and removable from the cap therewith, and means releasably holding the cap in place relative to the cylindrical outer shell.

18. In a thread tapping machine for apertured workpieces having predetermined contours, a tap having a stem extending from one end thereof, said stern including in the mid-region thereof a curved crank-type segment, cylindrical tap driving means encompassing and extending along said curved crank-type segment of the stem and including therein separable elements which together define an opening having a sectional shape and size conforming generally to said predetermined contours of the workpieces and providing a passage through which said workpieces are'slidable, said tap driving means being spaced from the tap longitudinally of the stern, means between the tap and the tap driving means for rotationally orienting the workpieces on the stem to positions for movement into said passage, said cylindrical tap driving means further including a hollow cylindrical shell and cap means for the cylindrical outer shell, a filler piece mounted in the cylindrical outer shell and having a slot therein and extending from end to end thereof for receiving said separable elements, said filler piece being secured to one end cap means for the cylindrical shell, and the other end cap means for the cylindrical outer shell being removable'from the shell for effecting removal of the separable elements and tap from the tap driving means.

19. In a machine having an electrical power circuit and adapted to form threads internally of workpieces of predetermined external size having central apertures of predetermined size therein, said machine having a thread forming tool, means for feeding said workpieces to the thread forming tool from a source of supply of such workpieces and which feeding means includes a wire having a sectional dimension fitting closely and slidably into the central apertures of the workpieces so that workpieces which have clogged, partially clogged or undersize apertures will not be received thereby, said means for feeding workpieces to the thread forming tool also including feeding rollers for sequentially transferring workpieces from the wire to the thread forming tool, one of said rollers having a support mounted for axial and trans-axial movements from a normal position, and switches mounted adjacent said support and actuatable by movements thereof beyond predetermined amounts, said switches being connected to control the electrical power circuit of the machine to stop the operation thereof when an oversize workpiece is encountered.

20. In a thread tapping machine, means for feeding workpieces to a tap having a fixed axis and rotationally driven at a substantially uniform speed and comprising, in combination, a plurality of generally cylindrical rollers, means supporting said rollers for rotation about axes parallel to and spaced laterally from the axis of the tap, said rollers having helical outer surface means by which the workpieces are moved longitudinally to, along and from the tap during rotation of the rollers, and means for driving the rollers at a speed proportional to the speed of rotation of the tap, said means supporting said rollers comprising shaft means for each roller, and each shaft means being supported relative to said tap for movements laterally of the axis of the tap from and toward substantially fixed positions relative to the tap.

References Cited by the Examiner UNITED STATES PATENTS 2/1906 Koester 10139 X 4/ 1925 Smith 10-129 10/1925 McCain 10133 5/1931 Raymond 10129 5/1939 Pruitt 10-139 11/1939 McLaughlin 10-139 10/1950 Hucal 10-139 FOREIGN PATENTS 3/ 1939 Germany. 11/ 1951 Germany.

15 ANDREW R. JUHASZ, Primal Examiner. 

1. A THREAD TAPPING MACHINE FOR SEQUENTIALLY CUTTING INTERNAL THREADS IN A SERIES OF APERTURED WORKPIECES OF SUBSTANTIALLY LIKE SIZE AND STRUCTURE AND COMPRISING IN COMBINATION, A SUPPORTING FRAME STRUCTURE, A TAP JOURNALLED FOR ROTATION ABOUT AN AXIS AND RELATIVE TO THE FRAME STRUCTURE, SAID TAP HAVING A CENTRAL CRANK-SHAPED STEM INCLUDING END REGIONS WHICH ARE SUBSTANTIALLY COAXIAL TO THE TAP AND A CURVED MID-REGION, SAID END AND MID-REGIONS BEING SMALLER DIAMETER THAN THAT OF THE TAP AND ALONG WHICH WORKPIECES MOVE AFTER PASSING ACROSS THE TAP, MEANS FOR FEEDING WORKPIECES TO THE END OF THE TAP OPPOSITE THE STEM AND INCLUDING ROLLERS SUPPORTED FOR ROTATION RELATIVE TO THE FRAME STRUCTURE AND HAVING AXES TO ROTATION SYMMETRICALLY DISPOSED ABOUT THE AXIS OF THE TAP, SAID ROLLERS EXTENDING ALONG SAID TAP AND BEYOND OPPOSITE ENDS THEREOF AND HAVING SURFACES ON THE PERIPHERIES THEREOF EXTENDING SPIRALLY THEREALONG FOR ENGAGEMENT WITH PORTIONS OF THE WORKPIECE THE STEM THEREOF TOWARD THE END OF THE TAP OPPOSITE THE STEM THEREOF DURING ROTATION OF THE ROLLERS, A PRIME MOVER, SEPARATE MEANS FOR DRIVING SAID ROLLERS, A PRIME MOVER, SEPARATE MEANS FOR DRIVING SUCH THAT THE MOVEMENTS OF THE WORKPIECES BY THE ROLLERS ARE SUBSEQUENTIALLY SYNCHRONIZED WITH THE NORMAL MOVEMENTS OF THE WORKPIECES ALONG THE TAP, AND MEANS FOR SUPPLYING WORKPIECES SEQUENTIALLY TO SAID MEANS FOR FEEDING THE WORKPIECES TO THE END OF THE TAP. 